From 5eeaeb6c3e1665dfa8b5ffa11277eff2ddded5ca Mon Sep 17 00:00:00 2001
From: "Dylan K. Taylor" <dktapps@pmmp.io>
Date: Sat, 22 Sep 2018 13:40:50 +0100
Subject: [PATCH] Level: Bail on trying to unload a level during level tick
 (#2435)

---
 src/pocketmine/level/Level.php | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/src/pocketmine/level/Level.php b/src/pocketmine/level/Level.php
index 5ad9d1686..ee7fddb1e 100644
--- a/src/pocketmine/level/Level.php
+++ b/src/pocketmine/level/Level.php
@@ -241,6 +241,9 @@ class Level implements ChunkManager, Metadatable{
 	/** @var int */
 	public $tickRateCounter = 0;
 
+	/** @var bool */
+	private $doingTick = false;
+
 	/** @var string|Generator */
 	private $generator;
 
@@ -528,8 +531,12 @@ class Level implements ChunkManager, Metadatable{
 	 * @param bool $force default false, force unload of default level
 	 *
 	 * @return bool
+	 * @throws \InvalidStateException if trying to unload a level during level tick
 	 */
 	public function unload(bool $force = false) : bool{
+		if($this->doingTick and !$force){
+			throw new \InvalidStateException("Cannot unload a level during level tick");
+		}
 
 		$ev = new LevelUnloadEvent($this);
 
@@ -697,7 +704,16 @@ class Level implements ChunkManager, Metadatable{
 		}
 
 		$this->timings->doTick->startTiming();
+		$this->doingTick = true;
+		try{
+			$this->actuallyDoTick($currentTick);
+		}finally{
+			$this->doingTick = false;
+			$this->timings->doTick->stopTiming();
+		}
+	}
 
+	protected function actuallyDoTick(int $currentTick) : void{
 		$this->checkTime();
 
 		$this->sunAnglePercentage = $this->computeSunAnglePercentage(); //Sun angle depends on the current time
@@ -818,8 +834,6 @@ class Level implements ChunkManager, Metadatable{
 		}
 
 		$this->chunkPackets = [];
-
-		$this->timings->doTick->stopTiming();
 	}
 
 	public function checkSleep(){